| Abstract: |
Conventional understanding of CD4 T cell development is that the MHC class II molecules on cortical thymic epithelial cell are necessary for positive selection, as demonstrated in mouse models. Clinical data, however, show that hematopoietic stem cells reconstitute CD4 T cells in patients devoid of MHC class II. Additionally, CD4 T cells generated from human stem cells in immunocompromised mice were restricted to human, but not mouse, MHC class II. These studies suggest an alternative pathway for CD4 T cell development that does not normally exist in mice. MHC class II is expressed on developing human thymocytes, indicating a possible role of MHC II on thymocytes for CD4 T cell generation. Therefore, we created mice in which MHC class II is expressed only on T lineage cells. Remarkably, the CD4 compartment in such mice is efficiently reconstituted with unique specificity, demonstrating a novel thymocyte-driven pathway of CD4 T cell selection. Copyright ©2005 by Elsevier Inc. |
| Keywords: |
signal transduction; controlled study; nonhuman; antigen expression; cell proliferation; t lymphocyte; animal cell; mouse; animals; mice; animal tissue; gene expression; cell maturation; cell line; animal experiment; cell lineage; mice, transgenic; stem cell; lymphocyte differentiation; receptors, antigen, t-cell; thymus gland; major histocompatibility antigen class 2; cd4-positive t-lymphocytes; epithelial cells; t-lymphocyte subsets; immune deficiency; genes, mhc class ii; thymocyte; cell selection; antigens, differentiation, t-lymphocyte
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